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Carbon fibre composites are light weight, high strength materials that are extensively used in the aerospace industry. For example, Boeing recently announced that at least 50 percent of the primary structure, including the fuselage and wings, on the 787 Dreamliner will be made of composite materials. The prohibitive costs of infrastructure investment and maintenance associate with the autoclave cure of composites have limited the uptake of these materials into new applications. The composite research group at Deakin University has a focus on out of autoclave composite manufacture, leading to the development and production of low-cost, high-performance composite components.
One of the out of autoclave techniques under research at Deakin is the Quickstep process. The Quickstep process utilises a balanced fluid filled mould to heat and cure the composite, the fluid having a much higher thermal conductivity than the gas used in an autoclave cure. This improvement results in cheaper and much faster cure cycles which facilitates the use of composites in non-aerospace applications such as automotive and rail applications.
Carbon fibre reinforced polymer (CFRP) composites manufactured by the Quickstep rapid heating-rate process exhibited interesting properties. A significant increase in interlaminar fracture toughness was observed for the investigated thermoplastic toughened carbon epoxy composite systems cured by the rapid heating-rate process comparing to those cured by the conventional autoclave process. This project aims to investigate the inherent mechanism of rapid heating- rate cure including the chemorheology, fibre/matrix adhesion and microstructural analysis.
Adhesives and mechanical fasteners have been a traditional approach to joining composite materials. However these approaches typically produce a discrete and often inefficient joint. A new approach that utilizes uncured composite pre-preg material to form seamless joins, known as melding, is being investigated. The process is known to produce a region where the composite material transitions from cured to uncured states. Current investigation seeks to characterize this transition and its impact on laminate properties after full cure has taken place. The project also aims to compare the mechanical behaviour and failure strength of joins produced using the melding process with both traditional joins and unitary structures.
The incorporation of silicate clays into both thermoplastic and thermosetting polymers in order to enhance mechanical properties is currently under investigation. A collaborative project with C.S.I.R.O. Textile and Fibre Technology is aimed at developing and producing spinnable novel materials by combining the use of nanoparticles and the blending of Nylon 6 with a semi aromatic polymer system. Another collaborative project with AINSE (the Australian Institute of Nuclear Science and Engineering) aims to enhance the understanding of structure property relationships in thermoset nanocomposites.
Low cost, out-of-autoclave processing (such as Resin Infusion and RTM) have had significant commercial application in recent history. Deakin's activity is focused on improving these processes further, specifically in the areas of lower cost tooling, toughness/damage tolerance and secondary bonding application. In-situ processing using these Infusion processes with a variety of heat application methods (such as Quickstep) are also being investigated.
The damage behaviour of quickstep cured composite panels is being studied in order to improve mechanical properties and durability of these materials that provide excellent thermal stability and low smoke and toxicity emission. This study involves both mechanical property characterization with various material parameters and Finite Element Analysis (FEA).
Automotive body panels made from carbon fibre composites offer significant vehicle weight savings and therefore reduced fuel consumption, however they are also expensive and difficult to manufacture, and retaining a Class A surface finish for the life of the panel is a major challenge. This project investigates autoclave curing versus a rapid composite curing process called Quickstep, to manufacture Class A carbon fibre composites, with the panel requirements for manufacturing Class A surfaces also investigated. The panels are subjected to accelerated aging environments along side with traditional steel panels with the degradation mechanisms compared.
The Quickstep process has been adapted to the task of manufacturing tubular profiles. Process optimisation has reduced the cure cycle just a few minutes with equivalent mechanical properties to existing processes. Axial compression has shown extremely high levels of energy absorption are possible with these lightweight structures, suitable for use in various energy absorbing applications such as vehicle bumper structures.
Accurate prediction of the crash behaviour of composites is essential if the automotive industry is to exploit the advantages inherent to this material. This project aims to use the explicit finite element code LS-DYNA, to simulate the axial crush behaviour of composite tubular structures with emphasis on including the failure mechanisms common to a splaying mode of collapse.
The development of bio-composite materials derived from biofibers or bioresins has recently become of interest due to the renewable ecofriendly nature and low cost of these materials. The main focus of this project is to produce bio-composites from renewable sources using the Quickstep process. Modification of the natural fibre surface with a low cost atmospheric plasma or plasma enhanced chemical vapour deposition is another important aspect of this research. A series of chemical and physical surface treatments will be employed in an effort to reduce the fibres inherent hydrophilic nature and also to improve the delamination behaviour of the composites.